A large number of valuable steroids drugs have substituents in the 17.alpha. position which are introduced by addition to a 17-ketone. A particularly important steroid of this type is 17.alpha.-ethynyl-19-nortestosterone (NET), a valuable progestational agent. The precursor 17-ketosteroid, 19-norandrost-4-en-3,17-dione (NAD) has been prepared by a variety of methods. In general, synthesis of this compound from bicyclic or tricyclic intermediates involves working with compounds wherein the eventual 17-keto group is protected, usually in a reduced oxidation state, for example, as an ester or ether of the 17.beta.-alcohol.
It would be valuable to have a synthetic method available that would afford a 17-ketosteroid wherein it was not necessary to utilize intermediates having a protected 17-ketone, but rather wherein such keto intermediates themselves could be utilized.